1. Health

Calcium and Drug Interactions

What Drugs Are Affected By Calcium Supplements?


Updated July 28, 2009

Certain medications or dietary supplements may interact with calcium supplements. You should inform your healthcare provider if you are taking any of the following along with calcium so that precautions may be taken or doses changed:
  • Calcium-containing medications: Ask your doctor or pharmacist if any of your medicines contain calcium, as taking them with calcium supplements can lead to excess calcium in the blood or urine, which may cause health problems.

  • Cellulose sodium phosphate: Calcium supplements may decrease the effectiveness of the drug.

  • Heart patients who use digitalis glycoside and take injections of calcium supplements are at increased risk for irregular heartbeat.

  • Sometimes the timing of other medications and calcium supplements can influence effectiveness. Etidronate is one of these drugs, and it should not be taken within 2 hours of calcium supplements.

  • Patients on gallium nitrate -- a drug that lowers blood calcium levels -- should discuss the use of calcium supplements with their doctor.

  • Using calcium supplements while receiving injections of magnesium sulfate can cause decreased effectiveness of both.

  • Calcium supplements should not be taken within 1 to 3 hours of phenytoin because the effectiveness of both may be decreased.

  • Antibiotics called tetracyclines (oral), when taken with calcium supplements, may lose effectiveness. If you are using tetracycline for an infection, be sure that you do not take calcium within 1 to 3 hours of taking the antibiotic.


CDC. Nutrition For Everyone. Basics. http://www.cdc.gov/nutrition/everyone/basics/vitamins/calcium.html. Accessed 07/19/09.

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